Semiconductor integrated circuit, display device provided with same, and control method

ABSTRACT

Disclosed herein is a semiconductor integrated circuit which controls the quality of an image and includes a viewer detector, a region specifier, and a controller. The viewer detector detects the number of viewer(s) watching the image and a gaze region being watched by the viewer within the image. If the number of viewers is plural, the region specifier specifies a local region of the image as a target region based on a plurality of gaze regions being watched by the viewers. The controller performs image quality control on the target region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of International Application No.PCT/JP2015/002893 filed on Jun. 10, 2015, which claims priority toJapanese Patent Application No. 2014-119586 filed on Jun. 10, 2014. Theentire disclosures of these applications are hereby incorporated byreference.

BACKGROUND

The present disclosure relates to a semiconductor integrated circuit foruse in, e.g., display devices, and more particularly, to a technique forreducing power consumption.

Nowadays, video displayed on display devices such as TV sets anddisplays is coming to have increasingly high definition. To achieve suchhigher video quality, display devices are required to perform a widervariety of processing and have enhanced performance Such processing toimprove the video quality results in increased cost of circuits andincreased power consumption, which is a problem. In particular, thelarger the screen size of a display device is, the more significantlythe cost and power consumption will increase.

To deal with such problems, a method of performing necessary processingon only a portion of a given screen, not on the entire screen, has beenstudied.

For example, Japanese Unexamined Patent Publication No. H01-141479discloses a device configured to perform encoding processing, not byuniformly allocating the same bit rate to the entire on-screen image,but by applying, based on the viewer's eye direction, a larger amount ofinformation to only a particular portion of the image to which he or sheis directing his or her eyes.

Also disclosed is a technique for performing stereoscopic videoprocessing when only one viewer is watching the video, whereas notperforming such processing when two or more viewers are watching it(see, e.g., Japanese Unexamined Patent Publication No. 2013-055675).

SUMMARY

The technique of Japanese Unexamined Patent Publication No. H01-141479is applicable to a situation where only one viewer is watching thevideo. Thus, if the technique of Japanese Unexamined Patent PublicationNo. H01-141479 was combined with the technique of Japanese UnexaminedPatent Publication No. 2013-055675, a portion of the on-screen imagewould not be processed in a situation where two or more viewers arewatching the video. That is to say, when two or more viewers arewatching video on, e.g., a TV set, the combination of these twotechniques would lead to failure to perform necessary processing on theentire screen. In that case, it would be difficult for each viewer towatch the video appropriately.

Conversely, performing necessary processing on the entire image on thescreen regardless of the number of viewers watching it could possiblycause an increase in power consumption and cost.

In view of the foregoing background, it is therefore an object of thepresent disclosure to provide a semiconductor integrated circuit capableof appropriately performing necessary processing on an image even if twoor more viewers are watching the same image and cutting down the powerconsumption and costs.

To overcome the problem described above, the present disclosure providesthe following solution. Specifically, a semiconductor integrated circuitfor controlling the quality of an image includes a viewer detector, aregion specifier, and a controller. The viewer detector detects thenumber of viewer(s) watching the image and a gaze region being watchedby the viewer within the image. If the number of viewers is plural, theregion specifier specifies a local region of the image as a targetregion based on a plurality of gaze regions being watched by theviewers. The controller performs image quality control on the targetregion.

According to this configuration, even if the number of viewers isplural, a local region of the image is specified as a target regionbased on gaze regions determined by, e.g., the eye or face directions ofthe viewers. Furthermore, the target region may be subjected to, e.g.,image quality improvement processing that allows the viewer to recognizehis or her target region more easily.

The target region may be identical with any of the gaze regions, or mayalso be a region in which some of the gaze regions overlap with eachother. The image quality control processing may be performed justlocally on the target region, not on the entire image on the screen.This may reduce not only the area of the range to be processed but alsothe required processing performance as well or may reduce the area ofthe range to be processed to reduce the required processing performance,which thus leads to a significant reduction in the power consumption andcosts of the semiconductor integrated circuit.

Also, a display device according to the present disclosure includes thesemiconductor integrated circuit. Thus, the power consumption and costsof the display device may also be reduced.

The present disclosure provides a semiconductor integrated circuitcapable of appropriately performing necessary processing on an imageeven if two or more viewers are watching the same image and cutting downthe power consumption and costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a semiconductor integrated circuitaccording to a first embodiment.

FIG. 2 is a flowchart showing exemplary processing of a semiconductorintegrated circuit according to the first embodiment.

FIG. 3 is a flowchart showing a first processing example to be performeduntil a target region is specified.

FIG. 4 is a flowchart showing a second processing example to beperformed until a target region is specified.

FIG. 5 is a flowchart showing a third processing example to be performeduntil a target region is specified.

FIG. 6 is a schematic diagram illustrating a display device according toa second embodiment.

FIG. 7 illustrates how a first exemplary set of gaze and target regionsmay be viewed in one situation.

FIG. 8 illustrates how the first exemplary set of gaze and targetregions may be viewed in another situation.

FIG. 9 illustrates how a second exemplary set of gaze and target regionsmay be viewed in one situation.

FIG. 10 illustrates how the second exemplary set of gaze and targetregions may be viewed in another situation.

FIG. 11 illustrates how a third exemplary set of gaze and target regionsmay be viewed in one situation.

FIG. 12 illustrates how the third exemplary set of gaze and targetregions may be viewed in another situation.

FIG. 13 illustrates how a fourth exemplary set of gaze and targetregions may be viewed in one situation.

FIG. 14 illustrates how the fourth exemplary set of gaze and targetregions may be viewed in another situation.

DETAILED DESCRIPTION First Embodiment

FIG. 1 is a block diagram of a semiconductor integrated circuitaccording to a first embodiment. A semiconductor integrated circuit 10is configured to control the quality of an image (which may be a movingpicture but will be hereinafter simply referred to as an “image”)displayed on a display device such as a TV set. The semiconductorintegrated circuit 10 includes an information input unit 12, a displayinformation input unit 14, an image generator 16, a viewer detector 18,a region specifier 20, a controller 22, and an output unit 24.

The information input unit 12 receives information about an image to bedisplayed on the display device. This information includes viewerinformation about viewer(s). The viewer information includes, e.g., thenumber of the viewers and a gaze region or gaze regions, and may beobtained from an imaging device such as a camera.

The information input unit 12 may also receive viewer information from,e.g., a sensor, a pair of dedicated glasses, or a speech recognizer.Examples of the viewer information may include information about his orher brain wave, heart rate, blood pressure, age, and gender, informationabout his or her feeling or emotion (e.g., his or her facialexpression), the distance from the display device to him or her, and theamount of time for which he or she is watching the gaze region (whichtime will be hereinafter referred to as a “gaze time”).

The display information input unit 14 receives display information to beoutput to the display device. The display information may include, e.g.,information about the image, compressed broadcast information, andcharacter information transmitted from a network, or may also beinformation which can be displayed on the display device (e.g., a stillpicture).

The image generator 16 generates, based on the display information,image information to be displayed on the display device and outputs it.That is to say, if the output of the image generator 16 is supplieddirectly to the display device, a normal image will be displayed on thedisplay device.

The image information may include character information or any otherkind of non-image information.

Also, for example, the display information input unit 14 may form anintegral part of the image generator 16, and the image generator 16 maybe provided outside the semiconductor integrated circuit 10 such thatits output is supplied to the semiconductor integrated circuit 10.

The viewer detector 18 may detect an arbitrary kind of informationincluded in the viewer information. For example, the viewer detector 18may detect, e.g., the number of the viewers and the gaze regionindicating a particular region being watched by the viewer within theimage. The gaze region may be a region having a predetermined rangewithin the image and having its center defined by a point at which theviewer is fixing his or her eyes, for example.

The viewer detector 18 may detect the gaze region by reference to, inaddition to or instead of the viewer's eye direction, his or her faceorientation or any other piece of information included in the viewerinformation.

The information input unit 12 may form an integral part of the viewerdetector 18.

The region specifier 20 specifies, as a target region, a local region ofthe image based on the number of the viewers and the gaze region thathave been detected by the viewer detector 18.

The target region may be a local region of the image to which one ormore viewers pay particular attention. For example, if there are aplurality of gaze regions (viewers), each of the gaze regions maypossibly be a target region, and either a region in which some of thegaze regions overlap with each other at least partially or any one ofthe gaze regions may be specified as the target region.

The region specifier 20 may take any other piece of information, such asthe distance and/or a gaze time, included in the output of the viewerdetector 18 into account in the processing step of specifying the targetregion. The output of the image generator 16 may also be supplied to theregion specifier 20. In that case, for example, the region specifier 20may specify the target region in consideration of image informationincluding character information as well.

The controller 22 performs, as image quality control of the targetregion within the image information output from the image generator 16,such processing that will make the target region more easily viewablefor the viewer, for example. That is to say, the region subjected to theimage quality control by the controller 22 is not the entire image onthe screen, but only a local region that would attract multiple viewers'attention deeply. The reason is that viewers generally tend to view onlya local region (e.g., a region including their object of interest) of animage more attentively. Accordingly, the controller 22 may perform,e.g., image quality improvement processing on the target region to allowthe target region to have higher image quality than the rest of theimage. Examples of the image quality improvement processing includeimprovement in definition using frequency information, and improvementin reproducibility of color information.

The output unit 24 outputs output image information subjected to theimage quality control by the controller 22. The output unit 24 may forman integral part of the controller 22.

The output image information is then actually displayed on the displaydevice.

Next, it will be described, with reference to FIG. 2, generally how thesemiconductor integrated circuit 10 according to this embodimentperforms processing.

FIG. 2 is a flowchart showing exemplary processing of the semiconductorintegrated circuit according to the first embodiment.

In Step S101, viewer information and display information are input tothe semiconductor integrated circuit 10.

In Step S102, the number of viewers and a gaze region are detected basedon the viewer information. Also, image information is generated based onthe display information.

In Step S103, the number of viewers is determined.

If the number of viewers is less than one, i.e., if there are noviewers, then there are no gaze regions. Thus, no target regions arespecified, and the process proceeds to Step S109. Accordingly, the imageis not subjected to the image quality control, and thus the entire imagekeeps its original image quality (for example, low image quality).

If the number of viewers is singular, his or her gaze region isspecified as a target region in Step S104.

On the other hand, if the number of viewers is plural, a determinationis made in Step S105 whether or not any of their respective gaze regionshas a region overlapping with another gaze region.

If there is any overlapping region (i.e., if the answer to the questionof Step S105 is YES), the overlapping region is specified as the targetregion in Step S106.

On the other hand, if there are no overlapping regions (i.e., if theanswer to the question of Step S105 is NO), the respective gaze regionsare specified as the target regions in Step S107.

When the target region(s) is/are specified, the target region(s) is/aresubjected, in Step S108, to image quality control such as image qualityimprovement processing to generate output image information. If thereare plural target regions, the image quality control is performed oneach of those regions.

Then, in Step S109, the output image information is provided from thesemiconductor integrated circuit 10.

As can be seen, according to the semiconductor integrated circuit 10 ofthis embodiment, even if two or more viewers are watching the sameimage, the image generated may have been subjected to such image qualitycontrol that would make the image viewable for each viewer to his or herpreference.

Japanese Unexamined Patent Publication No. H01-141479 discloses atechnique for weighting encoding processing of an image according to theviewers' eye directions. Japanese Unexamined Patent Publication No.2013-055675 discloses a technique for performing stereoscopic processingon an image only when a single viewer is watching the image withoutperforming such processing when two or more viewers are watching theimage.

Thus, a simple combination of the two techniques of Japanese UnexaminedPatent Publications No. H01-141479 and No. 2013-055675 would result infailure to process the image if two or more viewers are watching theimage. In addition, none of these techniques explicitly teach, if two ormore viewers are watching the image, how to specify a local region ofthe image, or subjecting that region to some image quality control suchas image quality improvement.

In contrast, according to this embodiment, the image quality control isalways performed on the target region regardless of the number ofviewers. This allows the respective viewers to watch the image to his orher preference.

In addition, the image quality control such as image quality improvementprocessing may be performed on only a local region of the image (i.e.,the target region), not the entire image on the screen, and thus, thearea of the range to be processed may be narrowed. This may reduce powerconsumption. Also, such a reduction in the area of the range to besubjected to the image quality control may require lower processingperformance than in a situation where the image quality control isperformed on the entire image. This may reduce costs and a circuit size.

Optionally, to further reduce power consumption and for other purposes,not all of the respective gaze regions have to be specified in Step S107as the target regions. That is to say, only a region in which some ofthe gaze regions overlap with each other may be specified as the targetregion.

In this embodiment, any other piece of information included in theoutput of the viewer detector 18 may also be taken into account duringthe processing to be performed until the target region is specified.Thus, some variations will be described below.

First Processing Example

FIG. 3 is a flowchart showing a first processing example to be performeduntil a target region is specified. The flowchart of FIG. 3 shows anexample in which a gaze time is used as a parameter. Note that it willnot be described how to detect the number of viewers in this example.

In Step S201, viewer information is input.

In Step S202, the gaze region and the gaze time are detected based onthe viewer information.

In Step S203, a determination is made whether or not there is any gazeregion being watched by the viewer for a longer time than the last time.That is to say, a determination is made whether or not there is any gazeregion being watched by the viewer more attentively.

If there are no gaze regions continuously watched for a longer time(i.e., if the answer to the question of Step 203 is NO), the range(area) of the gaze region is expanded in Step S204. That is to say, itcannot be said that the viewer is watching the gaze region attentively,and thus, the gaze region is not a candidate for the target region.

If there is any gaze region continuously watched for a longer time(i.e., if the answer to the question of Step 203 is YES), the range(area) of the gaze region is decreased in Step S205. That is to say, theviewer is watching the gaze region more attentively, and thus, the gazeregion may be regarded as a candidate for the target region.

In Step S206, the target region is specified based on the results ofSteps S204 and S205. For example, a gaze region having a predeterminedarea or less may be specified as a target region.

After that, the same series of processing steps will be repeatedlyperformed. Optionally, the area of the target region may be increased ordecreased according to the length of the gaze time after the targetregion has been specified from among the gaze regions. In other words,the gaze time may be included as parameters for determining the targetregion.

This further narrows down the target range of the image quality control,and thus results in a further reduction in power consumption and costs.

Second Processing Example

FIG. 4 is a flowchart showing a second processing example to beperformed until a target region is specified. The flowchart of FIG. 4shows an example in which shift of a gaze region within the image isused as a parameter. Note that it will not be described how to detectthe number of viewers in this example

In Step S301, viewer information is input.

In Step S302, the gaze region is detected based on the viewerinformation.

In Step S303, the magnitude of shift of the gaze region within the imageis calculated. That is to say, this shows how much the gaze region hasshifted within the image.

In Step S304, a determination is made whether or not the magnitude ofshift of the gaze region is equal to or more than a predetermined value.

If the magnitude of shift of the gaze region is equal to or more thanthe predetermined value (i.e., if the answer to the question of StepS304 is YES), the gaze region is excluded from candidates for the targetregion in Step S305.

On the other hand, if the magnitude of shift of the gaze region is lessthan the predetermined value (i.e., if the answer to the question ofStep S304 is NO), the gaze region is regarded as a candidate for thetarget region in Step S306.

In Step S307, the target region is specified based on the results ofSteps S305 and S306.

After that, the same series of processing steps will be repeatedlyperformed. As can be seen, even in a situation where the gaze regionshifts along with the movement of the viewer's eyes, it can be said thatthe gaze region is shifting relatively slowly as long as his or her eyemovement falls within a predetermined range. Thus, the gaze region maybe regarded as remaining at a fixed location within the image for apredetermined amount of time, and therefore, may be specified as thetarget region.

This may achieve the same or similar advantage as/to the firstprocessing example.

The semiconductor integrated circuit 10 may be provided with a memory orany other storage device to make the determination in Steps S203 andS304.

Third Processing Example

FIG. 5 is a flowchart showing a third processing example to be performeduntil a target region is specified. The flowchart shows an example inwhich the gaze region includes character information such as moviesubtitles and on-screen display (OSD). In this example, an image to beprocessed is a background image to be synthesized with the characterinformation. “A subtitle region including character information” refersherein to a region of the background image existing on the synthesizedimage and corresponding to a region including subtitles. That is to say,the synthesized image of the character information and the backgroundimage is not the image to be processed. This is because it would bebeneficial to perform the image processing on the premise that only theimage quality of the background image should be controllable,considering the fact that the background image with a relatively lowimage quality would allow the viewer to read the character informationmore easily in the vicinity of the region where the subtitles or OSDis/are synthesized with the background image. Note that it will not bedescribed how to detect the number of viewers in this example.

In Step S401, viewer information is input.

In Step S402, a gaze region is detected based on the viewer information.

In Step S403, a subtitle region including character information such asmovie subtitles or weather forecast is detected. Steps S402 and S403 maybe performed in reverse order.

In Step S404, a determination is made whether or not there is any gazeregion including any subtitle region. That is to say, a determination ismade whether or not the viewer is watching any subtitle region.

If there is any gaze region including a subtitle region (i.e., if theanswer to the question of Step S404 is NO), the gaze region is excludedfrom candidates for the target region in Step S405.

On the other hand, if there are no gaze regions including any subtitleregions (i.e., if the answer to the question of Step S404 is YES), thegaze region is regarded as a candidate for the target region in StepS406.

In Step S407, the target region is specified based on the results ofSteps S405 and S406.

After that, the same series of processing steps will be repeatedlyperformed. As can be seen, if the gaze region and the subtitle region atleast partially overlap with each other, excluding the gaze region fromthe target regions further narrows down the target range of the imagequality control. That is because it can be said that the image qualityimprovement or any other image quality control is required less oftenfor characters in an image than for persons and other subjects in theimage.

This may achieve the same or similar advantage as/to the firstprocessing example.

In the first to third processing examples, other pieces of informationincluded in the viewer information may also be used as parameters untilthe target information is specified.

For example, the shape of the gaze region may be changed in accordancewith the viewer posture information that has been input. Also, viewer'sspeech information or biological information about his or her brainwave, heart rate, or blood pressure may also be input to analyze thetarget watched by the viewer. For example, information about theviewer's feeling or emotions may be acquired based on his or her facialexpressions, and based on the information thus acquired, the degree ofimportance of the image (in particular, the target that the viewer iswatching) may be calculated to weight a plurality of target regions. Inthis case, the image quality may be controlled in accordance with thoseweights.

Optionally, any other piece of personal information about the viewersuch as his or her age or gender may also be used as a parameter forspecifying the target region.

The target region may also be specified by combining the first to thirdprocessing examples with one another.

Second Embodiment

FIG. 6 is a schematic diagram illustrating a display device according toa second embodiment. For example, a display device 30 configured as adigital TV set includes the semiconductor integrated circuit 10 of thefirst embodiment, an imaging device 32, a distance measuring sensor 34,and a display unit 36.

The imaging device 32 may be, e.g., a camera that captures an image of aviewer watching the image on the display unit 36, and may output viewerinformation to the semiconductor integrated circuit 10.

The distance measuring sensor 34 measures the distance between thedisplay unit 30 and the viewer, and outputs distance information to thesemiconductor integrated circuit 10. Optionally, the imaging device 32may be configured to have the function of the distance measuring sensor34.

The display unit 36 receives output image information from thesemiconductor integrated circuit 10 to display an image with qualitywhich has been controlled to the viewer's preference.

The semiconductor integrated circuit 10 receives display information viaan antenna which is not illustrated.

The image displayed on the display unit 36 of the display device 30having such a configuration also has a gaze region and a target regionto be described in detail below. Note that the semiconductor integratedcircuit 10, the imaging device 32, and the distance measuring sensor 34are not illustrated in any of the drawings to be referred to in thefollowing examples.

First Example

FIGS. 7 and 8 illustrate how a first exemplary set of gaze and targetregions may be viewed. In the examples shown in FIGS. 7 and 8, multiplewindows are displayed on the display unit 36.

For example, as illustrated in FIG. 7, suppose that multiple windowsW1-W4 are displayed on the display unit 36, and viewers A and B havestarted to view the windows W1 and W4, respectively.

In this case, the windows W1 and W4 are gaze regions 37 (as indicated bythe broken lines in FIG. 7), whereas the windows W2 and W3 are non-gazeregions. Thus, the windows W1 and W4 can be candidates for the targetregion, whereas the windows W2 and W3 are excluded from candidates forthe target region.

In this state, if the viewers A and B continue watching the windows W1and W4, respectively, the windows W1 and W4 are specified as the targetregions.

On the other hand, as illustrated in FIG. 8, if the viewer B startswatching the window W1, the viewers A and B are both viewing the samegaze region, and thus, the window W1 is specified as a target region 38(as indicated by the oblique lines in FIG. 8).

Second Example

FIGS. 9 and 10 illustrate how a second exemplary set of gaze and targetregions may be viewed. In the examples shown in FIGS. 9 and 10, a maleviewer A and a female viewer B are watching arbitrary regions on thedisplay unit 36.

For example, as illustrated in FIG. 9, suppose that the viewers A and Bhave started watching regions 37A and 37B, respectively, because of thedifference in their interest, for example.

In this case, the regions 37A and 37B are respectively gaze regions 37Aand 37B, and the other region on the display unit 36 is a non-gazeregion 39.

In this state, if the viewers A and B fix their eyes on the samelocations in the gaze regions 37A and 37B on the display unit 36 for apredetermined amount of time, for example, the gaze regions 37A and 37Bare specified as the target regions.

On the other hand, if the gaze regions 37A and 37B have shifted to thelocations illustrated in FIG. 10 because the objects of interest for theviewers A and B have moved, for example, the gaze regions 37A and 37Bpartially overlap with each other, and thus, their overlapping region(i.e., the region indicated by the oblique lines in FIG. 10) isspecified as the target region 38.

Alternatively, in FIG. 10, a region covering the gaze regions 37A and37B may also be specified as the target region 38.

Third Example

FIGS. 11 and 12 illustrate how a third exemplary set of gaze and targetregions may be viewed. In the examples shown in FIGS. 11 and 12, thedistance between the viewer A and the display device 30 is differentfrom the distance between the viewer B and the display device 30.

For example, as illustrated in FIG. 11, suppose that the viewers A and Bare watching the gaze regions 37A and 37B, respectively, from differentpositions.

The distance from the viewer A or B to the display device 30 may bemeasured by the distance measuring sensor 34 (see FIG. 6). Thus, if theviewer A is located at a longer distance from display device 30 than theviewer B is, the gaze region 37A may be excluded from candidates for thetarget region.

That is because it may be more difficult for a viewer located fartheraway from the display device 30 to sense improvement of the imagequality than for a viewer located closer to the display device 30.

As a result, as illustrated in FIG. 12, the gaze region 37B beingwatched by the viewer B located closer to the display unit 36 isspecified as the target region 38. Alternatively, if the viewer A hascome closer to the display device 30, the gaze region 37A may also bespecified as the target region 38. Still alternatively, if the viewer Bhas gone away from the display device 30, the gaze region 37B may alsobe excluded from candidates for the target region 38.

Yet alternatively, the gaze region being watched by the viewer locatedwithin a predetermined distance from the display device 30 may bespecified as the target region, instead of the gaze region being watchedby the viewer located closer to the display device 30.

In other words, the distance may be included in parameters fordetermining the target region.

Fourth Example

FIGS. 13 and 14 illustrate how a fourth exemplary set of gaze and targetregions may be viewed. In the example shown in FIGS. 13 and 14, an adultviewer A and a child viewer B are watching arbitrary regions on thedisplay unit 36.

For example, as illustrated in FIG. 13, suppose that the viewers A and Bare watching the gaze region 37A and 37B, respectively.

In this case, as illustrated in FIG. 14, the gaze region 37A isspecified as the target region 38, whereas the gaze region 37B isexcluded from candidates for the target region. That is because an adultwould sense an image of improved quality more easily than a child would.

As can be seen, in the first to fourth examples, subjecting the targetregion 38 to image quality improvement or any other type of imagequality control provides at least one of the viewers A and B with animage, of which the quality has been controlled to his or herpreference. In addition, the range to be subjected to the image qualitycontrol is narrower than the entire display unit 36. This leads to areduction in power consumption and costs.

In the first to fourth examples, a decimation process may be performedon the non-gaze region 39. Alternatively, any two or more of the firstto fourth examples may be arbitrarily combined with each other.

Optionally, settings of the image quality control of the target regionmay be adjusted with, e.g., a remote controller. If the target regionincludes a plurality of target regions, the specifics of the imagequality controls of the respective target regions may be setindependently of one another.

The image quality control does not have to be image quality improvementbut may also be any other type of control as long as it is beneficialfor the viewer. For example, the image may have its quality controlledby having its luminance, lightness, saturation, and/or hue adjusted orby having the edges of a person or any other object in the target regionenhanced such that the image will look clearer to the viewer's eyes.

Moreover, the area of the target region may be expanded to displayinformation about the person or any other object in the target region,or the image displayed within the target region may be zoomed in to makethe target region more clearly visible to the viewer. Such relevantinformation may be displayed on a mobile terminal owned by the viewer.

Optionally, the controller 22 may correct the output of the regionspecifier 20 based on the image information supplied from the imagegenerator 16. For example, the boundary or edges of the person or anyother object in the image information may be detected, and the imageinformation included in the target region may be corrected based on thedata. The controller 22 may receive tag information indicating detailsof the persons and other objects included in the image information. Inthis case, the image information included in the target region may becorrected based on this tag information.

If the viewer is watching a plurality of gaze regions intermittently,the history of the cumulative gaze time of each of those gaze regionsmay be recorded, and a gaze region, of which the cumulative gaze timehas reached a predetermined value, may be specified as the targetregion.

Moreover, the target region may also be specified in consideration ofthe order of viewing the image by plural viewers. Alternatively, therespective gaze regions, including a region in which some of the gazeregions overlap with one another, may be specified as the targetregions.

For example, unalterable information such as the viewer's age oreyesight or the owner of the display device 30 may be entered with,e.g., a remote controller. For example, the gaze region being watched bya viewer who is elderly or has weak eyesight or the gaze region beingwatched by the owner may be preferentially specified as the targetregion.

In the second embodiment described above, the display device isconfigured as a digital TV set. However, the display device may also beany other device such as a personal computer or a projector as long asthe device can display an image thereon.

A semiconductor integrated circuit according to the present disclosuremay perform, even if a plurality of viewers are watching the same imageon a display device, image quality improvement processing or any otherimage quality control on a region being watched by each of those viewersparticularly attentively. Thus, this circuit is useful for displaydevices such as large-screen TV sets and monitors that need to havetheir power consumption and costs reduced.

What is claimed is:
 1. A semiconductor integrated circuit for use in adisplay device, the circuit comprising an output unit, an informationinput unit, a viewer detector, a region specifier, and a controller,wherein the output unit outputs output image information to the displaydevice, the information input unit receives viewer information about oneor more viewers, in front of the display device, watching an image on asingle screen of the display device, the image being displayed based onthe output image information, the viewer detector is configured todetect (1) how many viewers are watching the image on the single screenof the display device and (2) one or more gaze regions within the imagebeing watched by the detected one or more viewers, based on the viewerinformation from the information input unit, the region specifier isconfigured to specify, in response to detecting a plurality of viewers,a target region in the image based on a plurality of gaze regions beingwatched by the plurality of viewers, the controller is configured toperform image quality control on the target region, and output the imageincluding the target region subjected to the image quality control asthe output image information to the output unit, the viewer detectordetects a distance between the one or more viewers and the displaydevice displaying the image, and the region specifier specifies thetarget region in consideration of the distance detected by the viewerdetector as well.
 2. The semiconductor integrated circuit of claim 1,wherein the region specifier specifies, as the target region, anoverlapping region in which two or more of the gaze regions overlap witheach other at least partially.
 3. The semiconductor integrated circuitof claim 1, wherein the controller performs image quality improvementprocessing as the image quality control.
 4. A semiconductor integratedcircuit for use in a display device, the circuit comprising an outputunit, an information input unit, a viewer detector, a region specifier,and a controller, wherein the output unit outputs output imageinformation to the display device, the information input unit receivesviewer information about one or more viewers, in front of the displaydevice, watching an image on a single screen of the display device, theimage being displayed based on the output image information, the viewerdetector is configured to detect (1) how many viewers are watching theimage on the single screen of the display device and (2) one or moregaze regions within the image being watched by the detected one or moreviewers, based on the viewer information from the information inputunit, the region specifier is configured to specify, in response todetecting a plurality of viewers, a target region in the image based ona plurality of gaze regions being watched by the plurality of viewers,the controller is configured to perform image quality control on thetarget region, and output the image including the target regionsubjected to the image quality control as the output image informationto the output unit, and if at least one of the gaze regions includescharacter information, the region specifier specifies the target regionby excluding the at least one gaze region including the characterinformation.
 5. The semiconductor integrated circuit of claim 1, whereinif any of the one or more gaze regions remains at a fixed locationwithin the image for a predetermined amount of time, the regionspecifier specifies the gaze region as the target region.
 6. Thesemiconductor integrated circuit of claim 1, wherein the viewer detectordetects the one or more viewers and the one or more gaze regions basedon information acquired from an imaging device capturing an imageincluding one or more viewers.
 7. The semiconductor integrated circuitof claim 1, further comprising an image generator configured to generatethe image.
 8. A display device comprising the semiconductor integratedcircuit of claim
 1. 9. The semiconductor integrated circuit of claim 1,wherein if the gaze regions do not overlap with one another, the regionspecifier specifies the gaze regions as target regions.
 10. Thesemiconductor integrated circuit of claim 9, wherein the controllerperforms, as the image quality control, multiple different types ofimage quality control on the gaze regions specified as the targetregions.
 11. The semiconductor integrated circuit of claim 10, whereinthe multiple different types of image quality control are determinedbased on the viewer information.
 12. A method of controlling a qualityof an image, the method comprising: a1) outputting output imageinformation, by an output unit, to a display device; a2) receivingviewer information about one or more viewers, in front of the displaydevice, watching the image on a single screen of the display device, theimage being displayed based on the output image information; a3)detecting that (1) how many viewers are watching the image on the singlescreen of the display device and (2) a plurality of gaze regions withinthe image being watched by the detected one or more viewers, based onthe viewer information; b) specifying a target region in the image basedon the plurality of gaze regions being watched by the plurality ofviewers; c) performing image quality control on the target region; andd) outputting the image including the target region subjected to theimage quality control as the output image information to the outputunit, wherein a3) includes detecting a distance between the one or moreviewers, and wherein b) includes specifying the target region inconsideration of the distance detected by the viewer detector as well.13. The method of claim 12, wherein c) includes performing image qualityimprovement processing as the image quality control.
 14. The method ofclaim 12, wherein b) includes specifying, if the gaze regions do notoverlap with one another, the gaze regions as the target regions. 15.The semiconductor integrated circuit of claim 1, further comprising: aninterface configured to output the image including the target regionsubjected to the image quality control to the display device.
 16. Thesemiconductor integrated circuit of claim 1, wherein the display deviceis a single display device, and the one or more viewers see the imagesdisplayed on the single display device.
 17. The method of claim 12,wherein c) includes emphasizing an edge of an image within the targetregion.
 18. The method of claim 12, wherein c) includes increasing adisplay magnification of the image within the target region.
 19. Themethod of claim 12, wherein c) includes transmitting information aboutthe image displayed within the target region to a mobile terminal theviewers own.